Strange Diesel engine problem

[Offtrack]

If anyone can point me to a decent Diesel mechanic near Dandenong, Vic, or give me some advice, I would really appreciate it.

One of our work Isuzu vans, similar to a Thrifty or Budget rental moving van has an ongoing problem. 2.0 litre non turbo Diesel.

On the Freeway, sitting on 100km/h, it will suddenly lose power and drop to 70-80km/h for 30 seconds or so, before slowly gaining speed back to 100km/h, and doing it again. This is with the accceletator flat to the floor the whole time. It feels as though you are climbing a steep hill, or hit a huge head wind....but it happens in ALL conditions, even doing down hill!

So far, we have done the following, all without any difference:

Changed fuel filter twice.
Changed Air Filter.
Changed Air filter hose between filter & engine (was too soft, and 'collapsing' under suction pressure).
Drained and cleaned Diesel tank. (found sludge & plastic bits from the fuel cap)
Used Diesel Power additive (thinking bad fuel)


This has been going on for several months now.

Any ideas?

[phil94delica]

Does it do it not long after you start off in the morning, then after it happens its fine for the rest of the day??

Id be guessing its a pump or injector fault, or computer if its electronic.

[Offtrack]

Does it do it not long after you start off in the morning, then after it happens its fine for the rest of the day??

Id be guessing its a pump or injector fault, or computer if its electronic.

All day, hot or cold.

From memory its a 2002 build - I'll have to check the details.

[KiwiBacon]

Air in the fuel?

[phil94delica]

Might be worth checking the strainer on the fuel pickup in the tank. Its cheap to check b4 spending money on getting the injection system checked.

[shorty_f0rty]

clutch!

i had that in my 40.. you'd loose power cept the rpms were the same/would go up.. but you'd be loosing speed.. check the tach (if it has one) next time it happens..

mechanic reckoned it was something to do with a diaphram on/in the clutch.. since the new clutch i haven't had the problem since..

[allterrain2000]

Check that the fuel tank is not presurising, my old 75 series fuel cap blocked and it didn't release the pressure in the tank.

Cheers
Jase

[Offtrack]

Check that the fuel tank is not presurising, my old 75 series fuel cap blocked and it didn't release the pressure in the tank.

Cheers
Jase

Fuel cap has been changed too!

Not sure about the RMP / clutch. I'll check that out.


Thanks for the sugestions.

[bogged]

take a nice drive to Andy at Diesel-tec in Lilydale.

or you have AG Diesel on westall road...

[Chucky]

It's not hitting the rev limiter is it?

[Offtrack]

It's not hitting the rev limiter is it?

It does..... But that doesn't explain the drop in speed. Hitting the rev limiter allows you to stay at the maximum RPM. I know this, from driving rentals..... Rev limiter, is the poor mans cruise control!!!

I'll give the Westall rd place a call.

[chimpboy]

How do they rev limit a diesel? Must be fuel rather than spark?

[trains]

How do they rev limit a diesel? Must be fuel rather than spark?

That is correct el Chimpo.

One reason why they can run away if they catch some diesel fumes.

T

[Dzltec]

It may be a fuel restriction or air entering the system, failing this possibly an injector pump problem.



Andy